The Xperia X is an upper-mid range (is that even a thing?) phone from Sony, which arrived in the United States about a year ago. It was pretty expensive for the specifications when it was released, priced at $549 in the US. But since then, it has continued to drop in price, and now you can get it for $214.99 from Amazon and B&H - the lowest price we've seen yet.
For the unacquainted, the Xperia X has a Snapdragon 650 CPU, 3GB of RAM, 32GB of expandable storage, a 23MP back camera, and a 13MP front shooter. The screen is a 5" 1080p LCD panel, and there is a 2,620mAh battery powering everything. The model for sale is the North American variant, which works on GSM carriers (complete with Band 12 for T-Mobile). For $215, this is definitely a good phone, especially considering it currently has Android 7.1.1. As far as I can tell, Sony has not yet announced if this will get Android Oreo.
You can find it on B&H and Amazon at the links below. If you want to buy it from Amazon, you'll have to wait a few more days for it to ship, as the phone is currently out of stock there (but orders are still accepted).